With ever-increasing operating frequencies of data and communication systems and an increased density of information to be transmitted, the electrical characteristics of connectors as mentioned above are of increasing importance. In particular, it has to be ensured that these modular jack type connectors do not have deleterious effects on the signals to be transmitted and that no additional interference is introduced. Based on these requirements, various proposals have been made in order to minimize negative influences, especially of modular jack connectors, used with communication or transmission links.
PCT Patent Application No. WO 98/54789 discloses a modular jack assembly which includes an outer insulative housing having top and bottom walls and opposed lateral walls defining a receptacle for a mateable modular plug connector. This assembly includes an insulative insert having a top section, an upper side and a rear section having a base side and a recess. This insert is positioned so that the upper side of its top section is adjacent to the top side of the insulative housing such that the terminals thereof extend into the receptacle. However, due to its configuration the insert is not apt to be used in a connector with a plurality of receptacles if these receptacles are arranged in more than one line. Different types of inserts would have to be used for such a design increasing costs arising from production of the different components and causing a more complicated assemblage.
PCT Patent Application No. WO 97/19499 proposes, in case of a RJ-45 modular jack, to use capacitors in an insert of the modular jack housing and contact sections held by the insert which contact sections are apt to mate with the contacts of an associated modular plug connector. In this way an attempt is made to obtain an impedance matching of the modular jack-type connector with the associated modular plug connector.
However, many interference signals are present on a transmission line, and may thereby considerably impair the transmission properties of the whole path consisting of transmission lines and associated connectors. As a result thereof, the attainable transmission rates are restricted, in particular in the data communication at higher frequencies, such as category 5, 6 or higher. Moreover, faulty transmissions and temporary breakdowns may occur when, e.g. low frequency interference signals or ripple loops are formed by magnetic induction or by electromagnetic interference on the line. Frequently, local potential differences of the ground potential between the transmission and reception locations are apt to severely reduce the desired signal amplitude.
For the elimination of in-phase interference signal noise components, U.S. Pat. No. 5,015,204 teaches use of a common-mode choke arranged in a connector housing around which the contact leads of a RJ-45 modular jack connector are integrally wound. In this design, the voluminous common-mode choke takes up a substantial portion of the connector housing, although only two signal-conducting leads are used. Furthermore, the respective leads need a certain rigidity to provide resilient forces to continuously facilitate a secure contact with the associated modular plug connector. However, this creates difficult manufacturing conditions, especially when the rigid wires, consisting of phosphor bronze, have to be wound around the conductive core of the choke coil.
U.S. Pat. No. 5,069,641 avoids such difficulties by the use of a printed circuit board to receive the common-mode choke coils or to receive electronic chip inductances. The printed circuit board not only requires its own space, but also needs several additional production steps in order to connect it to the components and the leads thereof.
U.S. Pat. No. 5,587,884 proposes transformers for signal conditioning for a transmission in IEEE 10 Base-T Ethernet networks. Modular jack designs proposed therein include, however, a multi-part insert which includes the electrical components and which insert clearly projects out from the rear portion of the modular jack housing. The insert includes an injection molded element in the region of the contacts for the associated modular jack connector, which injection molded element is intended to guide and stabilize these contacts. This results, in comparison to the conventional RJ-45 modular jack connector, in a significant increase in the connector housing's height and depth. These modular jack connectors are therefore, in many cases not suitable, e.g. if the required mounting space is restricted, for example, as in network hubs with numerous connections for associated modular jack connectors, or in adapters for PCMCIA cards.
It is an object of the invention to facilitate the suppression of interfering signals in a modular jack, and in particular to suppress interfering signals which arise on the transmission lines, and furthermore to provide a modular jack type connector which is apt to save mounting space and is simple to assemble.